Looking to the Past, Planning for the Future

Since giving my talk at TEAC2 several weeks ago on my proposed plan for our nuclear future, I’ve been spending a lot more time thinking about this issue, the plan, and how to describe what I would propose to do.

Sometimes it helps me to sort out thoughts by drawing a picture, but in this case, as I sketched out my plan, I found that I needed to sketch out descriptions of how nuclear operations have been conducted in the past, how they are conducted currently, and what the conventional view of our nuclear future is.

First of all, let’s consider the period right after World War 2. That may seem like a long time ago, but decisions were made then that still have ramifications to this day. In that time period, stretching from the late 40s until well into the 1960s, the overwhelming concern of the US Atomic Energy Commission (USAEC) was to produce weapons-grade plutonium and weapons-grade uranium for use in nuclear devices. Producing electrical energy from nuclear power was way down the list of priorities.

Here’s a sketch of how things worked back then. They would mine uranium and process the ore at a mill. Then some of the ore would be converted from natural uranium dioxide (the form it’s in in the earth) to uranium hexafluoride (UF6), which is a gas. When I say “natural” in these descriptions, I generally mean its isotopic consistency, in other words, that the proportions of U-235 and U-238 are the same as those found in nature (0.7% U-235 and 99.3% U-238 respectively).

So the NUF6 (natural uranium hexafluoride) would be enriched in a huge enrichment plant. Some of the first of these were in Oak Ridge, Tennessee, but later facilities were at Portsmouth, Ohio and Paducah, Kentucky. At these enrichment facilities, the composition of the uranium was changed at incredible expense. Most of the uranium ended up “depleted”, which means it has less U-235 than when it started. Some ended up “highly-enriched”, to the point where the uranium was nearly all U-235.

Another path was taken to make plutonium. This time, natural uranium was loaded into special heavy-water reactors at places like Savannah River that would lightly irradiate the uranium (I sometimes call it “toasted” uranium) in order to convert some of the abundant U-238 into plutonium-239. This plutonium was then separated chemically at an aqueous reprocessing facility and used for weapons construction.

Then we can take a look at how the nuclear approach looks today. We still mine uranium and enrich it, but now the enrichment level isn’t as high as is needed for weapons. Our reactors (at least in the US) don’t use “highly-enriched” uranium, they use low-enrichment uranium (LEU). It’s still produced in those big enrichment plants at great expense though. So we make LEUO2 fuel (low enrichment uranium oxide) and stick in our light-water reactors. As the fuel “burns”, plutonium is produced, but it doesn’t have the same composition as the weapons-grade stuff. It’s called “reactor-grade” plutonium.

We also have a lot of highly-enriched uranium that’s coming from the decommissioning of nuclear weapons. In a bizarre waste of energy, this HEU is being “downblended” with depleted uranium to also make nuclear fuel for light-water reactors. The energy investment originally required to make HEU was titanic, so downblending it is not my favorite idea for what we should be doing, but it’s what we’re doing nonetheless.

As you can see from the graph, our weapons-grade plutonium isn’t currently being used, and our small U233 inventory is sitting there too. We have a huge inventory of reactor-grade plutonium in our spent nuclear fuel, but the current plan (and it’s still law until they change the law) is to send it to Yucca Mountain.

Well, that doesn’t make any sense because Yucca’s been cancelled, right? So we turn to our next slide about the “conventional” view of our nuclear future. In this approach, we take the weapons-grade plutonium we have from decommissioned weapons and we make “MOX” fuel out of it. MOX stands for mixed-oxides, and it means that you have a fuel that is formed from plutonium and depleted uranium, and you mean to burn it up in a light-water reactor. Like LEUO2 fuel, you can only get part of the energy out of the MOX fuel that’s in there, so running it through the reactor doesn’t release all of the energy of the plutonium. But it does degrade it, probably enough that it’s no longer weapons-grade but now reactor-grade.

Our small U233 inventory, as I have bemoaned so many times, is slated for destruction in this scenario by mixing it with depleted uranium and burying it somewhere, probably in the Waste Isolation Pilot Plant (WIPP) facility in New Mexico.

It’s also possible that we might use aqueous reprocessing to recover reactor-grade plutonium from our light-water reactor fuel and make more MOX out of that, although the prospects for doing in this in the US aren’t so likely. France is doing this right now.

In this scenario, we still need a Yucca-Mountain type facility. We may reduce the need somewhat, but it’s still there.

Finally, we reach the scenario I propose, which is an attempt to completely destroy our weapons-grade plutonium and HEU while at the same time kick-starting our thorium-powered future into high gear. In my proposed scenario, we use the weapons-grade and reactor-grade plutonium in a liquid-chloride reactor. The liquid-chloride reactor can completely burn this stuff up, and if we jacket the reactor with thorium, we can make new U-233 to start all the LFTRs that we need to build to get energy independent.

We also stop downblending of HEU but use instead to start special versions of LFTR that are intended just to make more U-233. So these special LFTRs will live on a diet of HEU and produce U-233 in their blankets to start other LFTRs.

We take all of the spent, exposed uranium oxide fuel (XUO2) that our light-water reactors are producing and we fluorinate it. Most of it will come out as UF6 that we could send back to the enrichment plant if we want. The transuranic waste (TRU) which is mostly plutonium is sent to the chloride reactors to be burned up.

To make all of this happen we’re going to need a lot of fluorine to make all this fluoride salt. The average LFTR fuel is over 50% fluorine by weight. Here’s a chance to kill two birds with one stone. Most of the uranium we’ve ever mined is sitting outside of the enrichment plant in barrels as depleted uranium hexafluoride (DUF6). Each of those uranium atoms is locking up six fluorine atoms. Furthermore, disposing of depleted uranium in this chemical form (UF6) is a really bad idea. UF6 is chemically unstable, because the uranium is just barely holding on to those last two fluorine atoms. UF4 is much more stable, and UO2 is more stable than that (in nature). So we need to convert all of that DUF6 to DUO2 and recover lots and lots of fluorine. The recovered fluorine is then used to fluorinate spent uranium oxide fuel from light-water reactors, and to form new fuel and blanket salts for all the LFTRs we will build. Once DUO2 has been produced from DUF6, it could be disposed on in the same mines from whence it originally came. It will never be as radioactive as natural uranium (and its decay products).

In the scenario I lay out, the U-233 is precious, and we stop all efforts to destroy it. Rather, we want to make much more of it. We want LFTRs burning up HEU to make U-233. We want chloride reactors burning up plutonium to make U-233. Uranium-233 is the constraining factor in our thorium expansion because we have so little and we need so much.

The thorium itself will be easy to come by, provided that we begin to mine for rare-earth elements again, and stop relying wholly on Chinese imports. Thorium is always found with rare-earth elements, and will be available in large quantities for essentially no cost. They may actually even pay us to take it!

The goal of this plan is to address all of the heritage HEU and plutonium both from our weapons-program and from light-water reactor operation, as well as to get us off of fossil fuels and running on thorium. Another goal of this plan is to eliminate the need for a Yucca-Mountain style repository.

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45 thoughts on “Looking to the Past, Planning for the Future”

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How would you do things if you were allowed to engineer the system but weren't allowed to make liquid chloride reactors and had to use fast breeder reactors instead? That seems like a more likely scenario than the one you're outlining here, given how completely unproven liquid chloride reactors are. It would also be good to see how your proposed plan would transition once current stockpiles of random stuff are used up, especially what happens to those HEU-started LFTRS. Also, don't LFTRs produce a tiny bit of plutonium which should be fed back into the LCRs?

You have a number of steps where chemical as well as isotopic byproducts are used. Isn't the embodied energy in anything chemical a rounding error when you're talking about nuclear? (Except for uranium enrichment, that is. Even seeing the term 'downblending' in print makes me cringe.)

Totally agree about thorium being cheap to mine if we just start doing it, and there's plenty of other reason to mine rare earths other than thorium. China being the world's only major source of Neodymium is a very bad thing!

Hi Bram, if we couldn't have the liquid-chloride reactor I would probably recommend forgoing the fast-reactor part of the plan altogether and trying to start LFTRs on weapons-grade or reactor-grade plutonium. It would also probably mean that we couldn't entirely eliminate the need for a Yucca-style repository.

If I assume correctly that by "fast-breeder" you meant the conventional liquid-sodium-cooled, oxide or metallic-solid-fueled fast reactor, then my reason for not using it is that it cannot completely destroy the transuranic actinides. It can burn a bunch of them, smolder them somewhat, but it doesn't have a realistic prospect for completely getting rid of them. That's because the solid-fuel has to be reprocessed regularly, and each time you do that you lose a fraction of the fuel, and you've only burned a fraction up. If you're losing as much as 3% fuel per recycle and your burnup is short, you may not even break even on fuel generation.

Starting LFTRs on plutonium has a lot of drawbacks compared to starting them on U-233. Plutonium is far less soluble (as PuF3) in the salt than uranium (as UF4). Furthermore, in the thermal or intermediate spectrum of a LFTR, you've not going to burn off the higher actinides but simply shift the isotopic concentrations around. Eventually you'll have to pull the plutonium out and try to restart the reactor on pure U-233 (assuming you've bred enough in the blanket while you ran on Pu to make this possible).

LFTRs only produce a tiny amount of plutonium if you make no attempt to remove neptunium-237. Furthermore, the plutonium they make is Pu-238, which is not considered weapons-usable, and is in fact quite desired for RTGs for NASA deep-space missions. So it may be that the small amount of Pu produced in such a LFTR is one of its most valuable products! Look what Viking, Voyager, Galileo, Ulysses, and Cassini have done for us!

Bram, to answer other parts of your question, after the HEU-started LFTRs were done burning up all the HEU, we simply switch them to conventional LFTR mode by recycling the U233 produced in the blanket back into the core.

The chloride reactors are going to take a while to burn up all the plutonium, but eventually we start ratcheting them down as well, using the fuel from previous chloride reactors into ever smaller numbers until we're down to just a handful.

The endgame is a world powered essentially entirely by LFTRs and natural thorium fuel.

Another idea that I have been considering to obtain U233 is to use plutonium from aqueous reprocessing of LWR “waste” to make thoria-plutonia MOX fuel for use in existing LWRs, and then use fluorination and fluoride volatility reprocessing on the used thoria MOX.

This would avoid the need to develop either liquid chloride reactors or deploy sodium cooled fast reactors, but it would also suffer the previously mentioned disadvantage of failing to completely destroy plutonium and minor actinides.

I have to agree with the view that molten chloride reactors are the best solution to the LWR “waste” problem.

I really fail to see the logic of proposing an entirely new and likely far more expensive and risky R&D program to develop fast chloride reactors just to produce U233 start charges for fluoride-base reactors. Besides starting off Pu and other transuranics, any Two-Fluid Fluoride reactor can be simply started off low-enriched uranium in the fuel salt while the blanket produces U233 to be collected until it can be restarted on a pure Th-U233 cycle. Single Fluid designs can't do this but I know you prefer Two Fluid.

I know your response has been something regarding how you don't like the increased transuranics produced by such an operation and thus claiming we'd somehow still need Yucca Mountains. The fact is any proposed break-even pure Th-U233 design has provisions to process out and recycle the small amounts of transuranics produced (or they also need Yucca Mountains by that logic). In startup on LEU we simply use the same methods to process and recycle a few years worth of operation of the fuel salt until one switches to running off U233 (and the recycled transuranics from the first fuel salt). Thus all the transuranics also get eventually consumed. Even including the standard 0.1% processing loss, we would likely lose less TRUs to waste if we only did the process once after the 1 to 5 years needed (versus processing smaller amounts of TRUs but more often in the pure Th-U233 cycle).

I also disagree with the statement that if one starts a fluoride design on plutonium that at some point it has to be removed and thus is a waste issue. ORNL did propose removing and discarding Pu after it became less reactive (poorer isotope mix) because they had no concern over waste plutonium in the 60s and early 70s. All recent French modeling assumes keeping it all in until you reach the same equilibrium as with a pure Th-U233 cycle (with their newer fast spectrum and older MSBR-like cores). It works just fine, you just need a little bit more transuranics to start.

I really think you need to rethink the proposal of chloride based reactors. There are zero operational experience with these and far more uncertainty and R&D required.

Well, David, you're a smart guy and you've already anticipated most of my responses correctly. To those I will add the importance of minimizing the fissile start-charge of LFTRs in order to accelerate deployment. The French faster-spectrum fluoride reactors have much higher initial fissile inventory requirements.

I agree completely with you there. I think the French have gone down a wrong road with their very hard spectrum and need for very large start charges. Not as large as metal cooled fast breeders but getting pretty close.

Sorry for re-stating the obvious — especially given current events, vis the Nuclear Security Summit — but its plainly clear that there is exactly ZERO chance of running power reactors on HEU.
Anyone who thinks otherwise is dreaming in Technicolor.

I have a plan to get rid of HEU without making new plutonium. I have a plan to get rid of the need for uranium enrichment. The other approaches don't. They downblend and burn through the HEU quickly. Then they're still stuck with a world that needs enrichment.

I guess I dream in Technicolor, according to you. Wouldn't be the first time.

As an engineer, I like the idea of using two different reactor types to cover the market space. However rather than flouride/chloride or thermal/fast, I'd divide the market by proliferation & security sensativity.

Whether Jaro is right or wrong about HEU being a show-stopper, there is no doubt that it will cause resistance to LFTR acceptance (it's just a question of how much).

So I think we need both: 2-fluid thorium/U233 cycle LFTRs for more secure locations and single-fluid DMSRs for less secure locations. In the DMSR, the fissile material consists of low enriched U233/U235 and low grade Pu.

Once a DMSR gets cost optimized, it won't break-even, so it doesn't eliminate the need for ore mining and enrichment. I'm not convinced that makes a huge difference. It's 1950's technology, so even without a commercial market for it, it's unlikely to disappear forever from the face of the earth.

I am a supporter of fast reactors including the molten chloride design. There are two very obvious advantages. Firstly they are real TRU burners. Secondly there is a lot of DU and irradiated uranium lying around with a hot discussion on its disposal, currently by Blue Ribbon Panel.
Enrichment/downblending should be done to a standard 20% only. Any further downblending should be done only with thorium which provides not only neutron poison but also long term return of 'lent' neutrons as U-233.

I just returned from the ANS Student Conference a the University of Michigan and thought I should report the overwhelming support of Thorium and the LFTR. There were multiple research papers on Thorium presented by students and the U-233 petition was being passed around throughout the conference.

These kids are the future of the nuclear industry and they have open-minded ideas about the energy future. Based on what I saw & heard there is a very bright future for Thorium.

Olá Kirk!
Regarding all the Fluoride that is tied up by the world's Depleted UF6, I remember when working at Honeywell that the bulk price of anhydrous HF was ca. 10¢/lb. Back in the 80s, H2SO4, the main RM from which HF is made, ran 1-2¢ per pound, CaF2 rock cost a bit more, hence why HF – the cheapest industrial Fluoride – was and still *is* pretty cheap!

Let's look at what components and feeds for LFTR Fluids might benefit from the otherwise-wasted Fluoride ions of D-UF6:

3. Beryllium Fluoride. This is already produced in quantity as the pure precursor to Be metal. The Be-Fluorine bond however is so strong — beat only by the Alkali, Alk.Earth & R.E. metals — that the following reaction is strongly favored:
. . . . . . 3 BeSO4 +UF6 (~500C)–> 3 BeF2 +(UO2)SO4 +2 SO3(g).
Uranyl sulfate is easily pyrolized to U3O8/UO2, SO3 & O2, the BeF2 vacuum-distilled overhead (further purifying it) and the mixed U Oxides left as bottoms for burial.

Only in the case of Beryllium *might* the use of D.U Fluoride make sense, as BeSO4 is a precursor to BeF2 at Brush-Wellman. The sulfate is *not* particularly toxic, even to the 2% of those predisposed to Be-Lung Disease (neither is soluble BeF2 in that regard). So if B-W could offer clean *anhydrous* BeSO4 cheap enough (vs. BeF2), using D-UF6 to "Fluoridate" the Sulfate might fly…

Oh yeah, that whole nuclear proliferation problem. I guess downblending is politically necessary, but it should be done to just barely to the amount necessary to make the fuel no longer weapons grade. (And how do you downblend plutonium, anyway? Its not like it's chemically inseparable from anything in the same way that U235 and U238 are.)

Would it be possible for a liquid chloride reactor to burn up natural or spent/depleted uranium? If so it's a worthwhile technology to research in its own right.

There's nothing magic about "downblending" to 20% enrichment. That level of enrichment still has roughly 3/4 of the separative work already done on it (relative to natural uranium) to bring it to HEU status. Starting with 20% enriched uranium means you're much closer to your goal if you are a proliferative state.

So ask yourself, which is a better plan with regards to potential proliferation? One that continues to require uranium enrichment to maintain the nuclear enterprise, and continues to produce large amounts of reactor-grade plutonium?

Or one that eliminates HEU and all grades of plutonium, as well as the need for enrichment? A plan that uses a fissile material that absolutely minimizes the amount of fissile material for a given power generation level. A plan that uses a fissile material that has built-in detection features, and huge discouragements against use in a weapon.

The stronger response is that nuclear weapons aren't terribly hard to make, that reactors and warheads have about as much in common as fertilizer and conventional bombs, and that we should focus on building a society where people don't want to kill each other by any means.

That means clean energy. But more than that, it means trusting ourselves. Trusting ourselves to use synthetic fertilizer, or not — but not basing the decision on some miscellaneous facts about bombs.

You're absolutely right Kirk:
"There’s nothing magic about “downblending” to 20% enrichment. That level of enrichment still has roughly 3/4 of the separative work already done on it (relative to natural uranium) to bring it to HEU status. Starting with 20% enriched uranium means you’re much closer to your goal if you are a proliferative state."

However, if you keep repeating this often enough, you can bet that politicians will simply lower the definition of LEU from the current 20% to ~5% — the latter is already the downblending target of ex-weapons HEU: the maximum required by all the LWR in operation today, and also the enrichment level of the IAEA nuclear fuel bank — the first of which was just commissioned recently in Russia.

The goal of the people pushing downblending for "proliferation" reasons isn't proliferation, it's the extermination of nuclear power as an energy source. Look a little further and you'll find them backed by fossil fuel interests who stand to gain as long as nuclear power is suppressed.

That's why using HEU shouldn't be demonized any more than using nitrate fertilizer should be demonized. Both can be made into weapons, or used to tremendously enhance human life.

I'm fearful that introducing chloride reactor R&D into the proposal for development and deployment of LFTRs will increase the perceived overall program risk so much that LFTRs will never be funded (the perfect-is-enemy-of-the-good argument). It provides the anti-LFTR movement with an argument that the chloride reactor has never run, and it dulls the sharp argument that Oak Ridge has already demonstrated the molten fluoride salt reactor.

The opportunity to use chloride reactors to destroy inventories of weapons-grade plutonium can be introduced after LFTRs are successfully operating.

Jaro is rightly concerned that proliferation concerns might discourage running a reactor on HEU, but a LFTR would not require HEU except for the startup charge. I'm confident that the military security we use for continually, safely transporting thousands of nuclear weapons can be adapted for one-time per LFTR startups.

Isn't there a way to start up on 20% LEU and deal with the resulting messy plutonium chemistry?

In your diagram you show a flow of U233 from LFTRs to a U233 inventory. I believe we want to deploy LFTRs designed with 1.0000 Th/U conversion ratio, so that (a) they don't produce weapons usable U233 and (b) the internal U233 is maximally contaminated with U232 for self-protection.

Bob, there's no chronology on the chart, so I don't want to leave the impression that it all has to be present at the beginning.

LFTR would get developed first. Provided that we can save the 1000 kg of U-233, we can start about 1000 MWe of LFTRs before we run out of U-233 for start charges. The next phase would be to have a few LFTR-HEU reactors on secure sites, started and sustained on HEU, and dedicated to producing U-233. Their jobs would be to burn HEU and make U-233, not for themselves, but for other LFTRs that were not on the secure sites.

Only later, as the need for LFTR grows beyond about the 20-30 GWe level, does the plutonium-burning chloride reactor need to enter into the picture to provide the U-233 start charges to sustain an even faster build rate of LFTRs. But by this point LFTR will be a well-established commercial product.

I have written at length elsewhere on the current obsession with highly enriched uranium that is gripping the international discussion on nuclear matters at this moment over at Brave New Climate.http://bravenewclimate.com/2010/04/15/dv82xl/#com…

Some relevant passages from that post:

Putting an end to commercial use of HEU is going to cause problems of its own and these are not insignificant. In fact several countries are balking at the prospect and have said as much at the summit. Reading between the lines, it is also clear that their intransigence will be addressed at the G8 meeting later this year.

The two most widespread uses of HEU are as research reactor fuel and as targets for the production of medical and industrial isotopes. While few in number, test reactors, used for experimental fuel development for NPP, also need to be very powerful, and thus need enriched fuel. In addition to research and test reactors, there are also critical assemblies, subcritical assemblies, and pulse reactors that use fuels containing HEU. Critical and subcritical assemblies, for example, are typically used for either basic physics experimentation or to model the properties of proposed reactor cores, while pulsed reactors, are used to produce short, intensive power and radiation impacts.

High energy neutron beams can be used for some sorts of radiotherapy and for imaging very dense materials, an application of use to several industries. All this will end except in those places under the control of the governments of the NWS. Arguments that most of these applications can be redesigned to use low flux radiation are specious, as the throughput of these processes is sharply reduced. The NRU reactor, in its day could supply much of the world with medical isotopes, when it restarts, using LEU targets, it will supply Canadian needs only.

In short, activities that depend on high flux neutrons, in medicine, industry, and research, will be the private domain of those states that deploy nuclear weapons. This includes the development of nuclear energy, and power reactor design, which requires access to high flux neutrons to qualify material and assemblies, essentially closing the door on any further competition, (as well as the end of CANDU development) putting the NWS in virtual control of nuclear energy all over the globe, further extending their economic hegemony for the foreseeable future.

Kirk, regarding nitrate fertilizer, the regs have changed a lot since a few years ago.
Expect the same for HEU/LEU…..

A few notes:

The last known attempt by al-Qaeda to construct a fertilizer-based bomb in Europe came in 2003, when a cell operative bought 1,200 pounds of bagged Kemira GrowHow fertilizer for about $200 from an agricultural supply store in Britain.
Many European fertilizer manufacturers have since reduced the amount of ammonium nitrate, a key bomb ingredient, in their products.

Canada's two manufacturers (Agrium Incorporated and the J.R. Simplot Company of Brandon, Man.) decided voluntarily in 2005, for security reasons, to stop making the product.
Both were manufacturing ammonium nitrate for the agricultural market and both chose in light of 9/11 and the Oklahoma situation to stop production.

Some western farmers might still be using old stock and eastern vegetable farmers might still find ammonium nitrate profitable to import, but most farmers have switched to other fertilizers.

Garden centres don't carry the product except in a blended form.

"You can't walk into Home Depot and buy ammonium nitrate," said Susan Sykes, spokeswoman for the Canadian Fertilizer Institute in Ottawa.

The high nitrogen content would burn a lawn, she said, and only somebody with specialized soil knowledge would want it for a vegetable garden.

Industrial ammonium nitrate has always been strictly regulated and the agricultural industry recently introduced new security programs for the fertilizer.

A brochure, "On Guard for Canada," has been distributed to educate retailers about storage security, transportation and the need to keep sales records.
"Agri-retailers need to be on guard," says the guide, prominently advertised at http://www.caar.org

I don't know just how strictly regulated industrial ammonium nitrate is, as I recall being able to order it in 2000Kg lots from Brazil directly without too much problem at least up to four years ago. We where using in aqueous solution it to strip cadmium from high-tensile steels, and went through a lot of it.

But ether way there is a huge difference between the terms of the Dangerous Goods Act, and plans to totally eliminate the civil use of HEU regardless of the consequences to industry, research and medicine, which is what is being contemplated here.

The Nuclear Security Summit was posited on the principle that there's no difference between a Canadian nuke and a Iranian nuke. If you believe that, you'll be thrilled by the big breakthrough agreement of the summit: Canada, has agreed, along with similar rogue states like Chile and Mexico to ship their stocks of enriched uranium to the US. Peace in our time! I have here a piece of paper from the prime minister of Canada!